The invention relates to applying an extension force to a boutonniere deformity.
Boutonniere deformities occur in fingers and consist of a proximal interphalangeal joint that is flexed and a distal interphalangeal joint that is hyperextended. This deformity makes it difficult or impossible to extend the proximal interphalangeal joint. It is commonly caused by injury or by an inflammatory condition like rheumatoid arthritis.
A pseudoboutonniere deformity is a condition marked by proximal interphalangeal joint flexion contracture and restricted flexion of the distal interphalangeal joint. The characteristic hyperextension of the distal interphalangeal in boutonniere deformities is not present in pseudoboutonniere deformities.
Ring splints have been developed to straighten or realign interphalangeal joints of fingers and thumbs. One such ring splint includes two elliptical rings joined by an elliptical spacer as described in U.S. Pat. No. 4,932,396. The ring splint disclosed in U.S. Pat. No. 4,932,396 is described as being worn with the spacer over the joint on a boutonniere finger or mallet finger. In such a position, the ring splint is described as being capable of holding the finger in extension.